.login_form {
    display: block;
    width: 300px;
    height: 200px;
    border: 1px solid #000000;
    position: absolute;
    top:50%;
    left: 50%;
    margin-left: -150px;
    margin-top: -100px;
    padding:10px;
}
.login_user_name, .login_user_pword,.login_user_submit{
    display: block;
    height: 20px;
    margin-top: 30px;
    text-align: center;
}
.login_user_name label b, .login_user_pword label b{
    display: inline-block;
    width: 60px;
}